In this 1994 Hubble Space Telescope photograph, every bright object is a galaxy. Oddly - most of them are spiral galaxies. This rich cluster of galaxies, named CL 0939+4713, is almost half way across the visible universe. Photos like this indicate that clusters in the past contained a higher fraction of spirals than do nearby clusters which are usually dominated by elliptical galaxies.
On This Day in Space History
On December 7, 1972, Apollo 17 astronauts captured "The Blue Marble," one of the most reproduced photographs in history.
